Spark Plasma Sintering of High Entropy Alloys

High Entropy Alloys (HEAs) are a fairly new class of alloys and, although there is still discussion concerning a definitive classification of what an HEA is, they are typically characterised as having five or more principal alloying elements each at a concentration of 5% or higher. HEAs are currently the focus of much research as they have the potential to deliver improved properties over more conventional alloys. Such properties usually include improved mechanical performance and enhanced high-temperature properties. However, achievement of better properties is very dependent on the processing routes used to produce HEA material. This contribution focusses on processing routes that exploit high –pressure, especially the Spark Plasma Sintering (SPS) method, and also a promising new subset of HEA materials, namely HEA composite alloys (HEACs). While this field is still at an early stage of development some trends are beginning to emerge.